Mechanical refrigerator



p 2, 1941- E. A. BURNS 2,254,837

MECHANICAL REFRIGERATOR Filed July 8, 1958 INVENTOR. EAEL A.5umv5 ATTORNEY.

Patented Sept. 2, 1941 UNITED 'STATE S PATENT OFFICE MECHANICAL REFRIGERATOR Earl A. Burns, Detroit, Micln, assignor to Woodall Industries, Inc., Detroit, Mich a corporation of Michigan Application July 8, 1938, Serial No. 218,050

1 Claim.

My invention relates to improvements in mechanical refrigerators and particularly to an im- Fig. 3 is a cross-section taken on line 3-3 of Fig. 1, and

Fig. 4 is a cross-section taken on line 4-4 of Low frequency air-borne sound will set a large vibratory responsive panel, such as a metal panel, invibration in much the same manner as a mechanical vibrator will. For this reason it has been a common practice to load the metal walls adjacent to an air duct leaning to or away from I the mechanical compartment of a refrigerator Heretofore the noise arising in the mechanical compartment has escaped to the outer air through the air inlet to, or the outlet from, the mechanical compartment to the annoyance of the occupants of the residence wherein the refrigerator is situated. The sound vibrations arisingin the mechanical compartment of the refrigerator also set up responsive vibrations in the metal panels, which panels .are commonly used as wall panels surrounding said inlet or outlet openings and these induced vibrations aggravate the undesirable noise.

My improved refrigerator duct is so constructed that the duct walls are relatively unresponsive to noise vibrations arising within the mechanical compartment and such walls furthermore are of such a character as to absorb and damp out the sound vibrations within the frequency range that produces most of the disagreeable sound arising within the mechanical compartment.

More specifically, I have found that if the side walls of the air duct or ducts that lead to or from the mechanical compartment are formed of multi-ply material wherein one ply is a layer of relatively dense, inert, sound damping material, such as an asphaltum composition fiber board, and there is secured thereto in overlying relationship a liner ply of relatively loose porous highly sound absorbing material that the noise which arises in the mechanical compartment is substantially lessened and there is an absence of induced vibrations in the walls of the duct.

Other objects, advantages, and meritorious features of my invention will more fully appear from the following description, appended claim, and accompanying drawing, wherein:

Figure 1 is a side elevation of a refrigerator embodying my invention partly broken away to show the construction,

Fig. 2 is a rear elevation of the same refrigerator likewise partly broken away,

or the like with a damping material'such as asphalt saturated felt or some suitable spray-on plasticor the like. Loose, porous sound absorbing material has also been used as a liner for such metal walls, but such loose, porous sound absorbing material while eflicient and absorbing high frequency sound waves possesses little efficiency in absorbing low frequency sound and the sound which is produced in the mechanical compartment of a refrigerator or the like is low frequency sound of around 30 to 300 cycles per second.

I have found that if a multi-ply material is used to form the walls of an air duct leading to or away from the mechanical compartment of a mechanical refrigerator that by combining a relatively dense, inert, self-supporting sound damping layer which in itself constitutes a relatively unresponsive diaphragm with a liner of relatively .loose, porous sound absorbing material which in itself is highly eflicient and absorbent of high frequency sound, that such combined multi-ply structure is very efficient in substantially diminishing sound of low frequency. The loose, porous absorbing material is juxtaposed directly over the inert diaphragm layer and may be adhesively secured thereto to be supported thereby, and the low frequency sound arising in the mechanical compartment is substantially minimized and lessened and the construction is very eflicient.

In the drawing the conventional refrigerator is illustrated. It is shown as having a lower compartment within which the mechanical apparatus, collectively indicated by the numeral I0, is positioned. This apparatus may be spring supported as shown, minimizing the production of sound vibrations but a substantial amount of disagreeable noise is the usual result.

I prefer to form the bottom wall of this compartment of a layer of sound damping material I2 which may be a relatively inert dense composition fibrous layer carrying a substantial asphaltum content, such as is commercially sold under the name of "EB" board. This wall is provided with an air intake aperture ll shown in Fig. 4, and the rear wall of the compartment is provided with an outlet aperture ll shown in Fig. 2. I provide an air intake duct supported as shown in Fig. 8 below the bottom wall II. This duct has its wall formed of multi-ply material. The outer ply II is a relatively inert dense sheet which may be "KB, above specified. and which forms a relatively unresponsive diaphragm and is self-supporting. It is of thermoplastic character and may be shaped as shown and secured to the bottom wall I! as illustrated in Fig. 3. The multl-ply wall also includes a relatively thick liner layer 20 of loose, porous sound absorbing material. Various types of sound absorbing materials are available and may be used. Generally they are characterized as of a fibrous character and of light weight and highly porous and are good absorbing materials for sound of high frequency. A loose, fluil'y highly porous felt is suitable.

An insulation product known as Waddex and comprising a multiplicity of filmy tissue-like layers of cellulose material is a suitable product. Another commercial product known as Seapak," which is loose and highly porous. is also suitable. This sound absorbing layer is secured to the relatlvely inert layer it and may be adhesively secured thereto. It is supported thereby and is shown as overlying the same throughout the walls of the duct. This duct overlies the bottom wall i2 and extends away from the inlet opening II and toward the rear wall of the refrigerator, as shown, and has a substantial length.

Upon the rear wall oi the refrigerator there is provided an outlet duct of a similar character which communicates with the outlet opening it. This duct likewise has an outer wall ll of the same relatively dense inert type of material and a liner 2!! of a similar sound absorbing material. The rear wall of the refrigerator is not shown but is fashioned of this same inert material [2 as is the bottom wall and this exhaust duct is, therefore, a duct lined on three sides only and having the multi-ply wall on such three sides as shown in Fig. 4. It extends, however. for a subatantial distance up the rear wall of the refrigerator and due to its length it also functions to effectively minimize the disagreeable low frequency sound which arises within the mechanical compartment. Each of these du'cts. because of the character of the multi-ply wall, namely, the one layer of dense inert sound damping material which is self-supporting and the other layer of a porous highly absorbent material which overlies the dense inert diaphragm layer, serves very elliciently to minimize and reduce the low frequency soundwhich arises within the mechanical compartment.

What I claim:

A refrigerator having a mechanical compartment situated in its lower portion and provided with side walls, the bottom wall of said compartment having an air intake therethrough adjacent to the front of the refrigerator, an air duct communicating with said air intake and extending along underneath said bottom wall and communicating with the atmosphere adjacent to the rear of the refrigerator, said air duct having a wall formed of multi-ply material the outer ply of which is formed of relatively inert rigid sound damping fibrous material wherein the fibers are held together-by an adhesive binder and the inner ply of which is formed of relatively porous sound absorbing fibrous material wherein the fibers are loosely integrated. the rear wall of said compartment having an air outlet opening adjacent to the bottom wall, an air duct'communicating with said outlet opening and extending up along the rear wall of the refrigerator and communicating with the atmosphere at a point spaced substantially above said air outlet. said air duct being formed of multi-ply material the outer ply of which is formed ofrelatively inert rigid sound damping fibrous material wherein the fibers are held together by an adhesive binder and the inner ply of which is formed of relatively porous sound absorbing loosely integrated fibrous material secured to and supported by the outer ply.

EARL A. BURNS. 

